Chemistry 1 Chapter 5 Part I Light and Quantized Energy Last Updated December 2, 2018

Priority Standards

Michigan HSCE for Chemistry Big Idea Quantum theory provides a foundation for the atomic model and the understanding of electron behavior and arrangement. Core Concepts   Electrons are arranged in main energy levels with sublevels that specify particular shapes and geometry. Evidence for the movement of electrons between different energy levels can be observed through absorption and emission spectra. Michigan HSCE for Chemistry

Development of Atomic Model continued from previous notes To physicists, Rutherford’s model did not explain how an atoms e- are arranged in the space around the nucleus and also did not account for differences in chemical behavior. Development of Atomic Model continued from previous notes

Early 1900s Observation of light were made when elements were heated. Analysis of the light revealed that an elements chemical behavior is related to the arrangement of e- in its atoms

Electromagnetic Radiation Form of energy that exhibits wavelike behavior as it travels through space Includes visible light which is only a small portion of EMR (Visible Spectrum – ROY G BIV) Electromagnetic Radiation

Electromagnetic Spectrum

Greek Letter λ Lambda Shortest distance between equivalent points (Peak to Peak) Units = m, cm, nm nm=nanometers 1nm = 1 x 10-9m Wavelength

# of waves that pass a given point per second= Hz or 1/sec ν is Greek for nu # of waves that pass a given point per second= Hz or 1/sec 652 Hz=652 waves/sec=652/sec=652s-1 Frequency (ν)

Sketch and label the parts of a wave in your notes.

Amplitude=wave’s height Speed of light =3.00x 108 m/s in a vacuum Symbol is c Speed of light is a product of λ and ν c = λν All light travels at the same speed but with different wavelength and frequency

Speed of light Wavelength (m) Frequency (1/s or Hz)

Electromagnetic Spectrum= classifies light based on ν and λ ROY G BIV Quantum= the minimum amount of energy that can be lost or gained by an atom

Max Planck studied light emitted from heated objects, Proposed emitted light is quantized Equantum= energy h= Planck’s constant= 6.626 x 10-34 J.s J= Joules = Kg .m2/s2

ν= frequency Equantum = hν Planck’s Theory= for a given frequency matter can emit or absorb energy only in whole # multiples ( 1hν, 2hν, 3hν, 4hν)

Hydrogen’s Atomic Emission Spectrum

Photoelectric Effect = e- called photo electrons are emitted from metals surface when light of a certain frequency shines on surface

Einstein 1905- proposed EMR has both wavelike and particle like behaviors. Light can be thought of as a stream of tiny particles called photons. Photons have no mass but do have quantum of energy.

Einstein developed

Atomic Emission Spectra: a set of ν (frequencies) of light on the electromagnetic spectrum emitted by atoms of an element.